- Zarya Jorvet
- BBC Future*
In a strange corner of our solar system, there are two amorphous space masses.
They are about the size of continents, and they are believed to spend their time waiting for sustenance to fall on them, then sucking it in.
Their natural habitat is more exotic than their diet.
It can be described as “rocky”: around it there are strange minerals of unknown colors and shapes.
Otherwise, it is somewhat barren, save for the sea shimmering in the distance, and so vast that it contains the same amount of water as all the oceans on Earth combined.
Every day the “weather” is the same: a little warm 1,827 °CIts pressure in some areas is about 1.3 million times the pressure of the Earth’s surface.
In such a crushing environment, atoms deform and even the most common materials begin to behave very eccentric: Rocks are as flexible as plastic, while oxygen behaves like metal.
But this scorching hot spot isn’t on an alien planet, and those masses aren’t exactly wildlife.
It is, in fact, on the ground, only inside.
The environment in question is the lower mantle, the layer of rock that lies just above the planet’s core.
This mostly solid mantle is another world, a circular place dotted with a kaleidoscope of crystals, from diamonds (of which there are about a quadrillion tons) to minerals too rare to be found on Earth’s surface.
In fact, the most abundant rocks in this layer, the pergmanite and daphemaite, are largely a mystery to scientists.
They need very high pressures that are unique to the interior of the planet in order to develop and They collapse if brought into our world.
We can only see them in their natural form when they are trapped inside a diamond that reaches the surface. Even then, it is impossible to know what it actually looks like inside the Earth, as its physical properties vary so much in the pressures that they are usually found beneath.
for this part, who – which Far “ocean” does not contain a drop of liquid.
It is made of water trapped within the mineral olivine, which makes up more than 50% of the upper mantle. At deeper levels, it turns into indigo blue ringwoodite crystals.
“At those depths, the chemistry is completely changing,” says Vedran Lekic, associate professor of geology at the University of Maryland (USA).
“As far as we know, there are some minerals that are becoming more transparent,” he says.
But it is these amorphous masses that interest most geologists around the world.
In 1970, the Soviet Union embarked on one of the most ambitious exploration projects in human history: it tried to dig as deep as possible.
That solid layer of rock, sitting atop the Earth’s mostly solid mantle, and eventually partially molten, is the only part of the planet that the human eye has ever seen.
Nobody knows what will happen if they try to pass it.
In August 1994, the Kola superdeep well, located in the middle of an inhospitable stretch of arctic tundra in northeastern Russia, Reached amazing depthsIt extends up to 12,260 meters underground.
Initially, the team leading the project made predictions about what they expected to find, specifically that the Earth would heat up one degree for every 100 meters they cut toward its center.
However, it soon turned out that this was not so: in the mid-1980s, when they reached 10 km, the temperature was already 180 ° C, almost twice as much as expected.
But then the exercises were disrupted.
Under these harsh conditions, granite was no longer dreable: it behaved more like plastic than rock.
The experiment was stopped and no one has been able to cross the threshold of the crust to this day.
“We know much less about the Earth’s mantle than we do about outer space. – which we can observe using telescopes -, because everything we know is very indirect,” says Bernhard Steinberger, a researcher in geodynamics at the University of Oslo (Norway).
So how do you study an unseen or inaccessible environment, where the chemical properties of the most common materials are distorted beyond recognition?
Turns out there is another way.
Seismology involves the study of energy waves generated by the sudden movement of the Earth during massive events such as earthquakes.
Among them are the so-called “surface waves”, which are superficial, and “internal waves” that travel through the Earth’s interior.
To catch them, scientists use instruments on the other side of the world from earthquakes they detect and examine everything that has made its way.
By analyzing different wave patterns they can begin to piece together what could happen hundreds of miles underground.
It was these properties that allowed the Danish geophysicist Inge Lehmann to make an important discovery in 1936.
Seven years ago, a major earthquake in New Zealand led to a surprising seismic consequence: a kind of internal wave, which could travel through any material, managed to pass through the Earth, But it was “bent” due to an obstacle in the way.
Another type of wave, which cannot pass through liquids, was not able to pass through.
This overturned the long-held belief that the core was completely solid and led to the modern theory that there was a solid interior wrapped in a liquid outer shell, a kind of upside-down bogeyman, if you will.
Secret hidden in the depths
Over time, the method was improved, making it possible to visualize the hidden depths of the Earth in three dimensions, “using the same CT techniques” used in medicine, explains Leckic.
Almost immediately, this led to the discovery of two amorphous masses of Earth.
They are called Large Low Shear Velocity Provinces (LLSVPS), and they are two massive regions, where seismic waves meet resistance and slow down.
One of them called “Tuzu” is located under it Africa; The else“Jason”, is under the pacific ocean.
As with Earth’s core, these regions are distinctly different from the rest of the mantle and are some of the largest structures on the planet.
Their structures are thousands of kilometers wide and occupy 6% of the volume of the entire planet.
Estimates of their elevations vary, but Tozu is believed to be up to 800 kilometers in elevation, which equates to about 90 mountain peaks stacked on top of each other.
Jason can stretch at an altitude of 1,800 km, which translates to about 203 Mount Everest.
Their disfigured bodies cling to the core of the Earth, like amoebas on a speck of dust.
“There is 100% certainty that these two areas are, on average, slower [en términos de la rapidez con que las ondas sísmicas se mueven a través de ellas] from the surrounding area. This is not up for debate,” Lekich says.
“The problem is that our ability to see in that area is blurry.”
No matter how attractive their forms are, Almost everything else about them still not confirmedIncluding how it is formed, its components, and how it can affect our planet.
Scientists know something is going on there and are trying to figure out exactly what’s going on, believing that their understanding will help unravel some of the most enduring geological mysteries, such as how the Earth was formed, the ultimate fate of “ghost” planet Thea, and the inexplicable presence of volcanoes in certain parts of the world.
They can even shed light on the ways the Earth is likely to change over the next few millennia.
* If you want to know the different theories being considered about Tuzo and Jasonclick hereAnd read the original note on BBC Travel (In English)
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